The James Webb Space Telescope peered into a lonely dwarf galaxy and got brilliant results

The most powerful space telescope to date has focused an image of a lone dwarf galaxy in our galaxy’s neighborhood, photographing it in stunning detail.

About 3 million light-years from Earth, the dwarf galaxy, named Wolf-Lundmark-Melott (WLM) after the three astronomers involved in its discovery, is close enough for the James Webb Space Telescope (JWST) to be able to distinguish individual stars while remaining while being immobile. the possibility of simultaneously studying a large number of stars. The dwarf galaxy in the constellation Cetus is one of the most distant members of the local group of galaxies, which includes our galaxy. Its isolated nature and lack of interaction with other galaxies, including the Milky Way, make the WLM useful for studying the evolution of stars in smaller galaxies.

“We think the WLM doesn’t interact with other systems, which makes it very handy for testing our theories of galaxy formation and evolution,” said Kristen McQuinn, an astronomer at Rutgers University in New Jersey and lead researcher on the research project. Statement from the Space Telescope Science Institute in Maryland, where the observatory operates. “Many other nearby galaxies are intertwined and entangled with the Milky Way, making them difficult to study.”

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An image of the Wolf-Lundmark-Melotta dwarf galaxy taken by the near-infrared camera of the James Webb Space Telescope. (Image credit: NASA, ESA, CSA, STScI, Kristen McQuinn (Rutgers University)/Alyssa Pagan (STScI) and Zolt Levey (STScI))

McQuinn pointed to a second reason why the WLM is an intriguing target: its gas is very similar to that of galaxies in the early universe, without any heavier elements than hydrogen and helium.

But while the gas in these early galaxies never contained heavier elements, the gas in the WLM lost its share of those elements due to a phenomenon called the galactic wind. These winds come from supernovae or exploding stars; because the mass of the WLM is very small, these winds can push material out of the dwarf galaxy.

In the WLM image taken by JWST, McQuinn described the observation of many individual stars at different stages of their evolution with different colors, sizes, temperatures and ages. The image also shows clouds of molecular gas and dust called nebulae that contain the raw material for star formation in the WLM. In background galaxies, JWST can detect interesting features such as massive tidal tails, which are structures made up of stars, dust, and gas created by gravitational interactions between galaxies.

The main goal of the JWST in studying the WLM is to reconstruct the history of the birth of stars in a dwarf galaxy. “Low-mass stars can live for billions of years, meaning that some of the stars we see today in the WLM formed in the early universe,” McQuinn said. “By determining the properties of these low-mass stars (such as their age), we can get an idea of ​​what happened in the very distant past.”

Two views of the Wolf-Lundmark-Melotte dwarf galaxy: on the right, an image taken by NASA’s now-retired Spitzer Space Telescope, and on the right, a stunningly detailed observation of the same galaxy by the new James Webb Space Telescope. (Image credit: NASA, ESA, CSA, STScI, Kristen McQuinn (Rutgers University)/Alyssa Pagan (STScI) and Zolt Levey (STScI))

The work complements JWST’s study of galaxies in the early universe, and also allows telescope operators to test the calibration of the NIRCam instrument that produced the sparkling image. This is possible because both the Hubble Space Telescope and the now-retired Spitzer Space Telescope have already studied the dwarf galaxy, and scientists can compare images.

“We use the WLM as sort of a benchmark to make sure we understand the JWST observations,” McQuinn said. “We want to make sure that we measure the brightness of the stars very accurately and precisely. We also want to make sure we understand our near-infrared models of stellar evolution.”

McQuinn’s team is currently developing a software tool that anyone can use that can measure the brightness of all stars at individual resolutions in NIRCam images, she said.

“This is the main tool for astronomers around the world,” she said. “If you want to do something with the resolved stars that are gathered together in the sky, you need such a tool.”

The WLM group’s study is currently awaiting peer review.

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